docs: def num(self, count=None, show=None):  # (;$count,$show)
          """
          Set the number to be used in other method calls.
  
          Returns count.
  
          Set show to False to return '' instead.
  
          """
          if count is not None:
              try:
                  self.persistent_count = int(count)
              except ValueError:
                  raise BadNumValueError
              if (show is None) or show:
                  return str(count)
          else:
              self.persistent_count = None
          return ""